1. Field of the Invention
This invention relates to devices for drilling and boring through subterranean formations. More specifically, this invention relates to polycrystalline diamond compacts (PDCs), also known as cutting elements or diamond inserts, which are intended to be installed as the cutting element of a drill bit to be used for boring through rock in any application, such as oil, gas, mining, and/or geothermal exploration, requiring drilling through geological formations. Still more specifically, this invention relates to polycrystalline diamond inserts, which have a fully enclosed alternative material structure to minimize high tensile stresses in the diamond compact, minimize crack propagation, and to enhance abrasion resistance.
2. Description of Related Art
Polycrystalline diamond compacts (PDCs) are used in down hole tools, such as drill bits (including percussion bits; rolling cone bits, also referred to as rock bits; and drag bits, also called fixed cutter bits), reamers, stabilizers and tool joints. A number of different configurations, materials and geometries have been previously suggested to enhance the performance and/or working life of the PDC. Typically, PDCs have uniform internal regions, either being solid diamond, or, more commonly having a relatively thin diamond layer on the top or cutting surface of a solid carbide structure.
By way of introduction, a polycrystalline diamond compact (PDC), or cutting element, is typically fabricated by placing a cemented tungsten carbide substrate into a refractory metal container (can) with a layer of diamond crystal powder placed into the can adjacent to one face of the substrate. Additional cans are used to completely enclose the diamond powder and the carbide substrate. A number of such can assemblies are loaded into a high-pressure cell made from a low thermal conductivity extrudable material such as pyrophyllite or talc. The loaded high-pressure cell is then placed in a high-pressure press. The entire assembly is compressed under high pressure and temperature conditions. This causes the metal binder from the cemented carbide substrate to sweep from the substrate face through the diamond grains and to act as a reactive phase to promote the sintering of the diamond grains. The sintering of the diamond grains causes the formation of a polycrystalline diamond structure. As a result the diamond grains become mutually bonded to form a diamond mass over the substrate face. The metal binder may remain in the diamond layer within the pores of the polycrystalline structure or, alternatively, it may be removed via acid leaching and optionally replaced by another material forming so-called thermally stable diamond (TSD). Variations of this general process exist and are described in the related art. This detail is provided so the reader may become familiar with the concept of sintering a diamond layer onto a substrate to form a PDC insert. For more information concerning this process, the reader is directed to U.S. Pat. No. 3,745,623, issued to Wentorf Jr. et al., on Jul. 7, 1973.
For general background material, the reader is directed to the following United States Patents, each of which is hereby incorporated by reference in its entirety for the material contained therein.
U.S. Pat. No. 4,259,090 describes an improvement in the manufacture of diamond compacts in which a cylindrical mass of polycrystalline diamond is surrounded by and bonded to an outer mass of metal which provides support for the diamond.
U.S. Pat. No. 4,380,471 describes a polycrystalline diamond body infiltrated by a silicon atom-containing metal is bonded to a substrate, that comprises cemented carbide with a barrier of refractory material extending between the diamonds cemented together with silicon atom-containing binder and substrate substantially precluding migration of the cemented medium from the carbide substrate into contact with the silicon atom-containing bonding medium in the diamond body.
U.S. Pat. No. 4,466,938 describes a process for making compacts containing diamond, which reduces crystal flaws within the diamond.
U.S. Pat. No. 4,592,433 describes a cutting blank, preferably for use on a drill bit for cutting through earth formations, that comprises a substrate formed of a hard material and includes a cutting surface, with a plurality of shallow grooves, with strips of diamond disposed in the grooves.
U.S. Pat. No. 4,714,120 describes an earth boring bit that has a body with one end connected to a drill string member for rotation and has an opposite end with a matrix formed thereon. A plurality of cutting elements are mounted on the matrix for dislodging geological formations.
U.S. Pat. No. 4,984,642 describes a composite tool that comprises a sintered metal carbide support and a polycrystalline diamond active part having an inner surface of metallurgical connection to the support and an outwardly facing working surface.
U.S. Pat. No. 5,007,493 describes a cutting element retention system for a diamond drill bit.
U.S. Pat. No. 5,011,515 describes a compact blank for use in operations that require very high impact strength and abrasion resistance.
U.S. Pat. Nos. 5,045,092 and 5,158,148 describe cemented tungsten carbide rock bit inserts that has diamond particles dispersed therein for enhanced hardness and wear resistance.
U.S. Pat. No. 5,119,714 describes an earth boring bit of the type having one or more rotatable cones secured to bearing shafts, a cutting structure having diamond compacts used as wear resistant inserts.
U.S. Pat. No. 5,159,857 describes a single piece earth boring bit of the type having a body that includes a solid bit face on one end and a shank on the opposite end for connection in a drill string, and a cutting structure having diamond compacts used as wear resistant inserts.
U.S. Pat. No. 5,173,090 describes a method for manufacturing a diamond compact of the type used as a cutting insert.
U.S. Pat. No. 5,195,403 describes a method of producing a composite cutting insert for a twist drill that includes the steps of cutting an intermediate blank from a composite diamond compact.
U.S. Pat. No. 5,248,006 describes an earth boring bit of the type having one or more rotatable cones secured to bearing shafts, an improved cutting structure having diamond compacts used as wear resistant inserts.
U.S. Pat. No. 5,273,125 describes a single piece earth boring bit of the type having a body that includes a solid bit face on one end and a shank on the opposite end for connection in a drill string, an improved cutting structure having diamond compacts used as wear resistant inserts.
U.S. Pat. No. 5,310,512 describes a method and apparatus for producing a non-planar synthetic diamond structure of predetermined shape.
U.S. Pat. No. 5,441,817 describes a method for making diamond and CBN composites, under HP/HT conditions.
U.S. Pat. No. 5,451,430 describes a stress relieved CVD diamond that is produced by annealing said CVD diamond at a temperature above about 1100 to about 2200 degrees Centigrade in an non-oxidizing atmosphere at a low pressure or vacuum and for a suitable short period of time, which decreases with increasing annealing temperature so as to prevent graphitization of said diamond.
U.S. Pat. No. 5,469,927 describes a preform cutting element, particularly for a drag-type rotary drill bit, comprises a thin cutting table of polycrystalline diamond, a substrate of cemented tungsten carbide, and a transition layer between the cutting table and substrate, cutting table, transition layer, and substrate having been bonded together in a high pressure, high temperature press.
U.S. Pat. No. 5,484,330 describes an abrasive tool insert that comprises a cemented metallic substrate and a polycrystalline diamond layer formed thereon by high pressure, high temperature processing.
U.S. Pat. No. 5,486,137 describes an abrasive tool insert having an abrasive particle layer having an upper surface, an outer periphery, and a lower surface integrally formed on a substrate, which defines an interface therebetween.
U.S. Pat. No. 5,494,477 describes an abrasive tool insert that comprises a cemented substrate and a polycrystalline diamond layer formed thereon by high pressure, high temperature processing.
U.S. Pat. No. 5,501,909 describes a diamond substrate having a smooth surface, including a polycrystalline diamond film having a surface with a pit, and an insulating material other than diamond, which occupies the pit.
U.S. Pat. Nos. 5,510,193 and 5,603,070 describe a metal carbide supported polycrystalline diamond (PCD) compacts that have improved shear strength and impact resistance properties, and a method for making the same under high temperature/high pressure (HT/HP) processing conditions.
U.S. Pat. No. 5,524,719 describes an insert for drill bits that is formed with an elongate body, typically having a cylindrical cross section terminating at an exposed outer end, which is covered with a polycrystalline disc. The polycrystalline disk is reinforced with an insert, which is wholly captured in the polycrystalline material.
U.S. Pat. No. 5,560,754 describes a polycrystalline diamond and cubic boron nitride (CBN) composite compact and a method for making the same under high temperature/high pressure (HT/HP) processing.
U.S. Pat. No. 5,590,729 describes a cutting element for a rotary drill bit that includes a substantially planar table of superhard material having a cutting face and a cutting edge. The table may be reinforced against bending with one or more strut portions extending from the rear of the substrate and at least partially across the cutting element.
U.S. Pat. No. 5,662,720 describes a cutting element that comprises a diamond layer and metal carbide substrate. The diamond layer and the metal carbide substrate form an egg-carton shaped interface.
U.S. Pat. No. 5,669,271 describes a preform cutting element for a drag-type rotary drill bit that includes a facing table of polycrystalline diamond bonded to a less hard substrate, such as cemented tungsten carbide.
U.S. Pat. No. 5,672,395 describes a method for treating as as-grown chemical vapor deposited (CVD) starting diamond film having stresses and containing voids.
U.S. Pat. No. 5,743,346 describes an abrasive cutting element comprised of an abrasive cutting layer and a metal substrate wherein the interface therebetween has a tangential chamfer, the plane of which forms an angle of about 5 degrees to about 85 degrees with the plane of the surface of the cylindrical part of the metal substrate.
U.S. Pat. No. 5,804,321 describes a unitary article that is solid at a temperature in excess of about 1100 degrees Centigrade, which includes a diamond, a metal, and a brazing material brazing the diamond and the metal.
U.S. Pat. No. 5,819,862 describes downhole components for use in subsurface drilling.
U.S. Pat. No. 5,820,985 describes a polycrystalline diamond layer attached to a cemented metal carbide structure used as a cutter wherein the cutter has improved toughness or fracture resistance during use through the boron, beryllium or the like therein.